The present invention concerns a system for assisting the regeneration of depollution means integrated in an exhaust line of a motor vehicle diesel engine.
More particularly, the invention concerns such a system in which the engine is associated to common rail means for the supply of fuel to its cylinders, according to at least one post-injection.
Such a post-injection is, in a standard manner, an injection of fuel after the high dead center of the cylinder under consideration.
These supply means are adapted to implement at constant torque, through modification of parameters for controlling the operation of the engine, different regeneration strategies that make it possible to obtain different thermal states in the exhaust line.
Thus, for example, supply means implementing a first regeneration strategy according to a strategy called level 1 strategy and a second regeneration strategy according to a strategy called level 2 strategy and/or an over-calibrated level 2 strategy, have already been proposed.
Indeed, it is known that, to ensure the regeneration of depollution means such as a particle filter, the soot trapped therein is burned thanks to the thermal energy provided by the engine and to the exotherm obtained by the conversion of the HC and of the CO on means forming an oxidation catalyst placed, for example, upstream of the particle filter.
This combustion can be assisted by a catalyzing element mixed with the soot, coming, for example, from a regeneration assistance additive, mixed with the fuel for the supply of the engine, or by a catalyst deposited directly on the walls of the particle filter (catalyzed particle filter).
The higher the thermal levels in the exhaust line at the inlet of the particle filter, the shorter the duration of the filter regeneration.
However, in critical driving conditions, such as, for example, city driving or in traffic jams, the levels reached with standard regeneration strategies of the particle filter can become insufficient to ensure a correct regeneration of the filter, which can translate into regenerations that last very long and are thus highly fuel-consuming, or even incomplete.